child smog mask

young girl wearing protection mask to against air smog (© FAMILY STOCK -

Experts are calling it a “climate penalty” – the scourge of increasing surface-level ozone resulting from climate change.

Thanks to multiple pieces of legislation passed since the 1960s, we’re not breathing lead-laden fumes from cars and toxic black smoke from factories anymore. However, air quality is still heading in the wrong direction, threatening our health. The surface-level ozone concentration is rising now as we enter the summer season, with elevated risks of wildfires contributing to this threat. So, how harmful is this climate penalty, and is there any way to avoid it?

Surface-level ozone irritates the eyes, nose, and throat, but it’s especially dangerous to the respiratory system. It harms the airways and causes coughing and pain when taking a deep breath. It also predisposes people to colds, flu, and other respiratory infections and complications. Children are especially vulnerable, as are people with asthma, chronic bronchitis, emphysema, or heart disease. Older people and those who work and exercise outdoors are also at greater risk. In addition, surface-level ozone harms animals and plants and damages rubber, fabric, and paint.

Surface-level ozone, also known as ground-level ozone or tropospheric ozone, is a trace gas in the troposphere — the lowest level of the Earth’s atmosphere. It has an average concentration of 20-30 parts per billion, with higher levels in polluted areas. Surface ozone is formed through chemical reactions in the atmosphere when ultraviolet (UV) radiation from the Sun reacts with nitrogen oxides produced by combustion from cars, power plants, and factories. These mix with hydrocarbon compounds coming from those same sources of air pollution. In cities, vehicles make up 90 percent of the hydrocarbon load. These give smog its unpleasant odor.

people standing in city smog steam
Surface-level ozone irritates the eyes, nose, and throat, but it’s especially dangerous to the respiratory system. (Photo by Pétrin Express from Unsplash)

Thirty years from now, air quality over the United States is expected to be as bad as it was in the early 2000s, according to an assessment by First Street research firm in California. Warmer temperatures and climate-induced wildfires are expected to increase in number and severity. The smoke contains tiny particles which are inhaled and harm lung tissue. These substances are called particulate matter or PM2.5, and they are expected to increase in number.

First Street predicts that 400 counties in the United States that currently have zero pollution will become polluted. Heat waves are expected to increase to three times the current frequency and will be of longer duration. These are especially conducive to ozone spikes. The heat waves, along with higher temperatures, increased sunshine, and more areas with stagnant air, are expected to push the number of “bad air alert days” to nine days per year by the 2050s.

The National Climate Assessment has determined that there will be severe episodes of exceptionally poor air quality in the Northeastern U.S. and California. Year-round ozone will be rising the most in the Midwest.

Low-income individuals and minorities are especially at risk for these health issues triggered by surface-level ozone because they tend to live closer to the factories and oil refineries that belch out chemicals contributing to air pollution.

What can you do to stay healthy?

The Air Quality Index (AQI) tells you when air pollution is likely to reach levels that could be harmful. You can use the AQI as a tool to help you avoid particle pollution. Local TV stations, radio programs, and newspapers report the AQI. Try checking it when you’re planning your daily activities.

When ground-level ozone levels are high, limit the amount of air you breathe in while you’re outside. Spend more time indoors, where ozone levels are usually lower. Engage in less strenuous outdoor activities, like walking instead of running. If possible, do outdoor activities when ozone levels are lower – which is usually in the mornings and evenings.

About Dr. Faith Coleman

Dr. Coleman is a graduate of the University of New Mexico School of Medicine and holds a BA in journalism from UNM. She completed her family practice residency at Wm. Beaumont Hospital, Troy and Royal Oak, MI, consistently ranked among the United States Top 100 Hospitals by US News and World Report. Dr. Coleman writes on health, medicine, family, and parenting for online information services and educational materials for health care providers.

Our Editorial Process

StudyFinds publishes digestible, agenda-free, transparent research summaries that are intended to inform the reader as well as stir civil, educated debate. We do not agree nor disagree with any of the studies we post, rather, we encourage our readers to debate the veracity of the findings themselves. All articles published on StudyFinds are vetted by our editors prior to publication and include links back to the source or corresponding journal article, if possible.

Our Editorial Team

Steve Fink


Chris Melore


Sophia Naughton

Associate Editor